Oregon Zoo says it may never know why monkeys died

PORTLAND, Ore. -- An Oregon Zoo senior veterinarian said Wednesday that medical exams only ruled out causes but didn't point to a specific cause of death for six exotic monkeys.

A family of 9 cotton-top tamarin monkeys came to the Oregon Zoo last month. When they arrived they seemed healthy, but two days later six of them died.

Dr. Tim Storms said this is something that he's never seen in all of his experience.

"We were really wishing we could find a cause and not to know is really frustrating," he told KATU. "And really, you like to find an answer and make changes if necessary and it's difficult to know what to address in that situation."

He said they did find that all six monkeys suffered from shock, but that finding was too vague to point to a specific cause of death.

"There are other possible causes that we investigated and ruled out: extremes in temperature, toxins, pesticides. ... Some that were easy to rule out," he said. "More subtle things (tested for) were toxic elements in their foods which we assessed for and found no results to suggest that as a problem either."

Three of the nine monkeys survived. Storms told KATU they are in good health.